Conventional mass transfer via rotating packed beds provides a first fluid and a second fluid that are introduced to a permeable element(s) having a large interfacial area, and rotating the permeable element about an axis such that fluids flow through the pores of the permeable element to enhance the mass transfer between the two fluids. The concept of mass transfer via a rotating packed bed has been applied to synthesis of hypochlorous acid. Known rotating bed technology teaches that it is important to maximize the interstitial area of the porous element to maximize the surface area upon which liquid film is formed to enhance the mass transfer between the fluids. Conventional teaching focuses on maximizing the formation of surface film.